Mask etch processing apparatus

ABSTRACT

Method and apparatus for supporting and transferring a substrate in a semiconductor wafer processing system are provided. In one aspect, an apparatus is provided for supporting a substrate comprising a cover ring comprising a base having a bore disposed therethough, the base having an upper surface and one or more raised surfaces disposed adjacent the bore, wherein the raised surface comprise one or more first substrate support members disposed adjacent an edge of the bore and a capture ring disposed on the cover ring, the capture ring comprising a semi-circular annular ring having an inner perimeter corresponding to the bore of the cover ring and one or more second substrate support members disposed on the inner perimeter and adapted to receive a substrate, wherein the capture ring is adapted to mate with the cover ring and form one contiguous raised surface on the cover ring.

This application is a continuation of U.S. patent application Ser. No.10/689,783, filed Oct. 21, 2003 now U.S. Pat. No. 7,128,806, which ishereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to a method andapparatus for supporting and transferring substrates during photomaskfabrication.

2. Description of the Related Art

Semiconductor device geometries have dramatically decreased in sizesince such devices were first introduced several decades ago. Sincethen, integrated circuits have generally followed the two year/half-sizerule (often called Moore's Law), which states that the number of deviceson a chip doubles every two years. Today's fabrication plants areroutinely producing devices having 0.35 μm and even 0.18 μm featuresizes, and tomorrow's plants soon will be producing devices having evensmaller geometries.

Increasing circuit densities have placed additional demands on processesused to fabricate semi-conductor devices. For example, as circuitdensities increase, the widths of vias, contacts and other features, aswell as the dielectric materials between them, decrease to sub-microndimensions. However, the thickness of the dielectric layers remainssubstantially constant, with the result that the aspect ratios for thefeatures, i.e., their height divided by width, increases. Reliableformation of high aspect ratio features is important to the success ofsub-micron technology and to the continued effort to increase circuitdensity and quality of individual substrates and die.

High aspect ratio features are conventionally formed by patterning asurface of a substrate to define the dimensions of the features and thenetching the substrate to remove material and define the features. Toform high aspect ratio features with a desired ratio of height to width,the dimensions of the features are required to be formed with certainparameters, which is typically defined as the critical dimensions of thefeatures. Reliable formation of high aspect ratio features with desiredcritical dimensions requires precise patterning and subsequent etchingof the substrate.

A technique commonly used to form precise patterns on substrates isphotolithography. In conventional photolithographic processes, aphotoresist material is applied on a substrate layer to be etched. Alight source emitting ultraviolet (UV) light is typically used to exposethe photoresist layer to chemically alter the composition of thephotoresist. However, the photoresist layer is only selectively exposed.In this respect, a photomask, or “reticle,” is positioned between thelight source and the substrate being processed. The photomask containsthe desired configuration of features for the substrate. The exposed, oralternatively, the unexposed photoresist material is then removed toexpose the underlying material of the substrate. The retainedphotoresist material remains as an etch resistant pattern on thesubstrate. The exposed underlying material may then be etched to formthe desired features in the substrate, i.e., contacts, vias, or otherfeatures.

Photolithographic photomasks, or reticles, typically comprise asubstrate of an optically transparent silicon based material, such asquartz. A light-shielding layer of metal, typically chromium, ispatterned on the surface of the substrate. The metal layer is patternedand etched to form features which define the pattern, and correspond tothe dimensions of the features to be transferred to a substrate, such asa semiconductor wafer.

The deposition and etching processes employed to fabricate the photomaskrequires that the substrate be transferred and supported within aprocessing system. It has become desirable to utilize processingequipment and systems which are configured for processing the substratesthemselves when fabricating the photomasks. However, these systems aretypically configured to process circular substrates, and must bereconfigured to support and transfer rectangular photomasks. Inaddition, the systems used to support and transport the substrates usedin photomask fabrication must carefully handle the substrates to preventscratches and other defects from being formed on the substrates. Thesedefects can alter the light transmission properties of the substratesand result in defective photomasks.

Therefore, there is a need for a method and apparatus for transferringand supporting substrates in processing systems which minimizes defectformation.

SUMMARY OF THE INVENTION

The present invention generally provides a substrate support member tominimize defect formation in a substrate during processing and handlingof substrates in a plasma etch chamber. In one aspect, an apparatus isprovided for supporting a substrate on a pedestal or cathode in aprocessing chamber to minimize contact between the substrate and thechamber components during processing.

In one aspect, an apparatus is provided for supporting a substratecomprising a cover ring comprising a base having a bore disposedtherethough, the base having an upper surface and one or more raisedsurfaces disposed adjacent the bore, wherein the raised surface compriseone or more first substrate support members disposed adjacent an edge ofthe bore and a capture ring disposed on the cover ring, the capture ringcomprising a semi-circular annular ring having an inner perimetercorresponding to the bore of the cover ring and one or more secondsubstrate support members disposed on the inner perimeter and adapted toreceive a substrate, wherein the capture ring is adapted to mate withthe cover ring and form one contiguous raised surface on the cover ring.

The apparatus for supporting a substrate may be used in a processingchamber comprising an enclosure defining a process region, whichprocessing chamber may also be used in a substrate processing systemcomprising a transfer chamber, at least the one processing chamber, anda substrate handler disposed in the transfer chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a schematic view of one embodiment of an etching chambercontaining a substrate support member;

FIG. 2 is an exploded perspective view of the substrate support memberof FIG. 1;

FIG. 3 is a top plan view of one embodiment of a cover ring;

FIG. 4 is a cross-sectional view of the cover ring of FIG. 3;

FIG. 5 is a schematic top view of one embodiment of a capture ring;

FIG. 6 is a schematic bottom view of the capture ring of FIG. 5;

FIG. 7 is a schematic cross-sectional view of one embodiment of asubstrate support;

FIG. 8 is a cross-sectional view of the a substrate in a processingposition in relation to the substrate supports;

FIG. 9 is a perspective view of the substrate handler of the inventionin relation to the capture ring of the invention;

FIG. 10 is a perspective view of FIG. 9;

FIG. 11 is a perspective view of the substrate handler of the inventionin relation to the capture ring of the invention;

FIG. 12 is perspective view of a substrate in the capture ring of theinvention;

FIG. 13 is perspective view of a substrate in the capture ring of theinvention;

FIG. 14 is a top schematic view of a radial cluster tool for batchprocessing of semiconductor substrates.

DETAILED DESCRIPTION

Aspects of the invention will be described below in reference to aninductively coupled plasma etch chamber. Suitable inductively coupledplasma etch chambers include the ETEC Tetra™ photomask etch chambers,such as the ETEC Tetra I™ photomask etch chamber and the ETEC Tetra II™photomask etch chamber, available from ETEC of Hayward, Calif., oroptionally, a Decoupled Plasma Source DPS™ processing chambers, such asthe DPS I™, DPS II™, and DPS+™ processing chambers available fromApplied Materials, Inc., of Santa Clara, Calif.

Other process chambers may be used including, for example, capacitivelycoupled parallel plate chambers and magnetically enhanced ion etchchambers, as well as inductively coupled plasma etch chambers ofdifferent designs. Examples of such suitable processing chambers aredisclosed in U.S. patent application Ser. No. 09/325,026, filed on Jun.3, 1999, which is incorporated by reference to the extent notinconsistent with the claims and disclosures described herein. Althoughthe processes are advantageously performed with the DPS™ processingchamber, the description in conjunction with the DPS™ processing chamberis illustrative and should not be construed or interpreted to limit thescope of aspects of the invention.

FIG. 1 is a schematic cross sectional view of one embodiment of aprocess chamber 160 having a substrate support member disposed thereinand a substrate handler blade 300 positioned adjacent thereto. Theprocess chamber 160 generally includes a cylindrical side wall orchamber body 162, an energy transparent dome ceiling 163 and a chamberbottom 167. An inductive coil 176 is disposed around at least a portionof the dome 163. The chamber body 162 and chamber bottom 167 of thechamber 160 can be made from a metal, such as anodized aluminum, and thedome 163 can be made of an energy transparent material such as a ceramicor other dielectric material. A substrate support member 100, such as acathode assembly, is disposed in the chamber 160 to support a substrate222 during processing. A plasma zone 164 is defined by the processchamber 160 above an upper surface of the substrate support member 100.A top housing (not shown) generally encloses the process chamber 160.

Process gases are introduced into the plasma etch chamber 160 through agas distributor 172 peripherally disposed about the substrate supportmember 100. The gas distributor is shown illustratively, and may bedisposed in other configurations, such as disposed at the top of dome163. Process gases and etchant byproducts are exhausted from the processchamber 160 through an exhaust system 180. A throttle valve 182 isprovided in an exhaust port 184 for controlling the pressure in theplasma etch chamber 160. An endpoint measurement device may be includedto determine the endpoint of a process performed in the chamber.

The substrate support member 100 has a substrate support assembly 115disposed thereon. The substrate support assembly 115 includes a capturering 120 having one or more substrate support members disposed thereonor otherwise connected thereto disposed on a cover ring 116 having oneor more substrate support members to receive and support a substrate forprocessing in the chamber 160. The substrate support member 100 will bedefined in more detail below, and the cooperation of the substratesupport member 100 with a substrate handler blade will be described andillustrated below.

A cathode 112 (not shown in FIG. 1) is disposed in the base 106 of thesubstrate support member 100 and is electrically coupled to an electrodepower supply 178 to generate a capacitive electric field in the plasmaetch chamber 160. Typically an RF voltage is applied to the cathode 112of the substrate support member 100 while the chamber body 162 iselectrically grounded. The capacitive electric field forms a bias whichaccelerates inductively formed plasma species toward the substrate 222to provide a more vertically oriented anisotropic etching of thesubstrate 222.

FIG. 2 is an exploded perspective view of one embodiment of a substratesupport member 100. The substrate support member 100 includes a body106, a substrate supporting assembly 115 including a cover ring 116 anda capture ring 120. The body 106 is mounted on a bulk head assembly, orshaft, 102. In the embodiment shown, the body 106 is stationary in thechamber, however, in an alternative embodiment, the body 106 or aportion of the body 106 may be moveable within the chamber. The cathode112 disposed in the base 106 may vertically extend above the surface ofthe body 106. Channels 111 (three are shown) are also disposed throughthe body 106 and house internally movable lift pins 114 therein. Thelift pins 114 engage the lower surface of the capture ring 120 to movethe capture ring vertically within the chamber relative to the coverring 116. The body 106 may comprise a temperature controlled baseadapted to regulate the temperature of the substrate support assembly115, and thus, a substrate 222 disposed thereon. The body 106 can bemade of a material inert to the process formed in the processing chamberincluding, for example, aluminum oxide, or aluminum, and substratesupport assembly 115 components can be made of aluminum or aluminumoxide. The body 106 may include fluid channels, heating elements, e.g.,resistive heating elements or other temperature control members.

The body 106 of the substrate support member 100 is mounted on astainless steel base 104, typically disposed on the bottom of aprocessing chamber (not shown); with the bulk head assembly 102 mountedthrough the bottom of the processing chamber and coupled to the body106. The substrate support member 100 is adapted to maintain vacuumisolation between the interior of the chamber and the outsideenvironment. Power, electrical controls, and backpressure gases areprovided to the substrate support member 100 via the shaft 102.

Referring to FIG. 3, a top view of one embodiment of a cover ring 116,and FIG. 4, a cross-sectional view of FIG. 3, the cover ring 116includes a base circular ring with an upper surface 119 and raisedsurfaces 121, 122 disposed thereon. A central opening or bore 125 isdefined in the upper surface 119 of the cover ring 116. The uppersurface 119 and the raised surfaces 121, 122 may be monolithic or may bemade of separate components connected together. The raised surfaces 121,122 include a linear raised surface 122 extending along the length ofone side of the bore 125 and an arcuate raised surface 121 with an outerdiameter 124 co-existing with the radius of the ring and an innerperimeter 126 conforming to the shape of the bore on one or more sidesof the bore. Substrate supports 118 are disposed on the raised surfaces121, 122 of the cover ring 116 and around the perimeter of the bore 125of the capture ring 120 and form a continuous substrate supportingsurface when the capture ring 120 and cover ring 116 are integrated. Thesubstrate supports 118 include substrate receiving surfaces defined byan inner sloped surface of each substrate support 118.

Channels 117 are formed through the cover ring 116 to enable the liftpins 114 disposed through the body 106 to move therethough and lift thecapture ring 120 vertically. The vertical movement imparted by the liftpins 114 is used to lift the capture ring 120 to effectuate substratetransfer between a substrate handler blade 300 and the capture ring 120.The actuation of the assembly 115 will be described in more detailbelow.

The capture ring 120 includes an arcuate base plate 202 having an innerperimeter 207 defining a bore 206 therein. A plurality of substratesupports, such as substrate supports 204, 205, are disposed on the innerperimeter 207. The substrate supports 204, 205 and the base plate 202define a substrate receiving area. The substrate supports 204, 205 andthe base plate 202 are adapted to mate with the substrate supports 118on the cover ring mate when contacting the cover ring 116 and thecapture ring 120 and define a planar substrate receiving surface forprocessing. The lift pins 114 move the capture ring 120 vertically abovethe cover ring 116 during substrate transfer and then lower the capturering onto the cover ring 116 for processing. The whole assembly 115 maythen be moved vertically within the chamber 160.

FIG. 5 is a top view of one embodiment of a capture ring 120. Thecapture ring 120 includes a base 202 having an inner perimeter 207 andtwo substrate supports 204, 205 disposed therein. The base 202 isgenerally an arcuate ring with the central opening 206 defined therein.The base 202 is adapted for mounting on the cover ring 116. The base 202further includes a circumferential sealing lip 210 formed at theperimeter of the base 202 which forms a seal with the processing chamber(shown in FIG. 1) when the substrate support member 100 is positioned inan upper processing position. A seal formed between the sealing lip 210and the chamber prevents gases from flowing behind the substrate supportmember in contact with the lower portion of the chamber.

The substrate support members 204, 205 of the inner perimeter 207 definean opening 220 through which a substrate handler blade can be moved totransfer a substrate (shown and described below in reference to FIGS.9-13) with minimal contact between components of the system.

FIG. 6 is a bottom view of the capture ring 120 of FIG. 5. A pluralityof lift pin recesses 224 are formed in the base 202 around the opening206 and are adapted to receive the lift pins 114. The lift pin recesses224 are spaced around the perimeter of the capture ring 120 to providestable support for the capture ring 120 when the capture ring 120 islifted into a raised position. The lift pins 114 and lift pin recesses224 can also be used to align the capture ring 120 on the cover ring116.

FIG. 7 is a sectional view of the substrate support members 204, 205 ofthe capture ring 120 and substrate support members 118 of the cover ring116. The substrate support members 204 include an upper surface 212, anouter surface 213 and an inner surface 215. The inner surface 215includes an upper substrate aligning surface 214 which is disposed at anincline from the upper surface 212. The upper aligning surface 214provides gravity assisted gross alignment of a substrate 222 receivedthereon. The upper aligning surface 214 may have an angle from thenormal of between about 5° and about 30°, such as 15°. A generallyvertical substrate capturing surface 217 is provided below the substratealigning surface 214 and defines an outer boundary of a substratereceiving area. The lower portion 216 of the substrate support member204 has an inclined surface disposed at an angle between about 2° andabout 7°, preferably between about 2.5° and about 5°, for example, about2.5°. The inclination of the substrate support members 204 minimizes thesurface area contact between the substrate 222 and the substrate supportmembers 204, 205. The inclined surface and the lower portion 216 alsoassist in centering the substrate as it is received thereon.

The capture ring 120 and cover ring 116 are generally formed from of anetch resistant, high temperature resistant material, such as aluminum oraluminum oxide, to enable the capture ring 120 and cover ring 116 to beused repetitively in the etching process without damage such asscratching or deformation. The capture ring 120 and cover ring 116 arepreferably formed from single pieces of material to ensure a good fitwith each other. However, the capture ring 120 and cover ring 116 may bemade of multiple components, for example, the raised surfaces of thecover ring 116 may be made of a separate material and bound to the uppersurface of the cover ring 116.

FIG. 8 is a cross sectional view of the substrate supports of the coverring 116 and capture ring of the substrate 222 in a processing position.The substrate supporting ridge 225 of the cathode 112 defines asupporting surface on which the substrate is supported duringprocessing. A space 170 is defined between the substrate supportingridge 225 and a lower surface of a substrate 222 when the substrate 222is received on the substrate supporting ridge 225. A backside gas can beflowed into the space 170 during processing to facilitate thermalconduction and to prevent process gases from being introduced behind thesubstrate 222. The backside gas can be delivered into the space 170, forexample, by the backside gas line 188 disposed in the pedestal 116 froma remotely located backside gas source 190 through gas portals (notshown) to the surface of the cathode 112.

To sufficiently transfer heat from the substrate 222 to the substratesupport member 100 and prevent backside contamination, a substantial gaspressure may exist beneath the substrate 222. A clamp ring (not shown)may be fitted to the periphery of the capture ring 120 to retain thesubstrate 222 on the substrate support member 100 when substantialbackside gas pressure is applied between the substrate support member100 and the substrate 222. Such a clamp ring would be similar to thatused to retain a substrate on a substrate support member 100 in a MxP™chamber of a P5000™ platform, as manufactured by Applied Materials, Inc.of Santa Clara, Calif.

FIGS. 9-14 illustrate transfer of a substrate 222 from the blade 300 tothe capture ring 120. The blade 300 retrieves a substrate 222 from aloadlock chamber 416 and delivers the substrate 222 into the processingchamber 412 (shown in FIG. 14). One example of a suitable blade 300 forhandling the substrate is more fully described in U.S. Pat. No.6,537,011, issued on Mar. 25, 2003, which is incorporated by referenceherein to the extent not inconsistent with the disclosure and claimedaspects herein. The substrate 222 disposed on the blade 300 is thenhorizontally aligned with the capture ring 120 in a vertically displacedposition as described above and shown in FIGS. 5, 9, and 10.

The capture ring 120 may then be moved upwardly by lift pins 114 tocontact and lift the substrate 222 off the blade 300 as shown in FIG.11. The lower portion 216 of the substrate supports 204, 205 lift thesubstrate 222 from the blade 300. The vertical displacement of thecapture ring 120 is sufficient to allow to the blade 300 to withdrawfrom the processing chamber without contacting the top surface 202 ofthe capture ring 120 or the bottom surface of the substrate 222 as shownin FIG. 12. Once the blade is withdrawn, the capture ring 120 is loweredby the lift pins onto the upper surface 119 of the cover ring 116 forprocessing as shown in FIG. 13.

For retrieving a processed substrate 222 from the capture ring 120, thecapture ring 120 is vertically displaced from the cover ring 116 to thesubstrate transfer position. The substrate handler blade 300 enters theprocessing chamber 160 and aligns the blade 300 between the substrate222 and the top surface 202 of the capture ring 120 as illustrated byFIG. 11. When the blade 300 is aligned with the capture ring 120, theblade 300 is disposed in a vertically displaced position below theinclined lower portions 216 of the substrate support members 204, 205.The capture ring 120 is then lowered and the substrate handler blade 300supports the substrate 222 thereon as illustrated by FIG. 10. Thecapture ring 120 is vertically displaced in a lowered position to allowthe blade 300 to withdraw from the chamber 160 without contact with thecapture ring 120 as shown in FIG. 9. In the lowered position, thecapture ring 120 is ready to receive another substrate from the blade300. The substrate handler blade withdraws from the chamber 160 toreturn the processed substrate to another chamber, for example, aloadlock chamber 416 and then to retrieve another substrate 222 forplacement in the processing chamber 160.

The supporting apparatus and substrate handler blade 300 described abovemay also be taken advantage of in a substrate processing system 410providing support for a substrate. The substrate processing system 410may include a transfer chamber 414, at least one processing chamber 160with a substrate support member 100 with a support surface and a capturering coupled to the support surface, the capture ring adapted receive asubstrate, and a substrate handler 418 disposed in the transfer chamber414. The substrate handler 418 preferably has a substrate handler blade300 described above. The process chambers are preferably plasma etchchambers.

FIG. 14 is a plan view of a vacuum cluster tool 410 suitable for usewith the apparatus of the invention described above. The vacuum clustertool includes multiple substrate processing chambers 412 mounted on acentralized vacuum chamber 414, such as a transfer chamber, fortransferring substrates from a substrate cassette located in one or moreload lock chambers 416, to one or more process chambers 412. A clustertool similar to that shown in FIG. 14 is a Centura™ processing systemavailable from Applied Materials, Inc. of Santa Clara, Calif.

Transfer of the substrates between the process chambers 412 is typicallymanaged by a substrate handling module, or substrate handler, 418,preferably with the substrate handling blade 300 mounted thereon. Thesubstrate handler 418 is located in the central transfer chamber 414.After the substrates are processed, the substrates are retrieved fromthe processing chambers 412 and transferred to one or more of the loadlock chamber 416 and into one or more substrate cassette (not shown)disposed within the one or more load lock chambers 416. The substratescan then be retrieved from the loadlock chambers 416 and transferred tothe next system for additional processing. In photomask manufacturingprocessing, the process chambers 412 are etching chambers, preferablyplasma etching chambers.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. An apparatus for supporting a reticle, comprising: a substratesupport pedestal having an upwardly extending substrate supportingridge; a cover ring disposed on the substrate support pedestal, thecover ring having a plurality of lift pin holes and spaced raisedfeatures for retaining a reticle therebetween, the cover ring having acentral opening through which the substrate supporting ridge extends; acapture ring disposed on the cover ring and having a substratesupporting feature; and a plurality of movable lift pins disposed in thesubstrate support pedestal and actuatable through the cover ring to movethe capture ring, relative to the cover ring, to a position thatsupports the reticle above the cover ring.
 2. The apparatus of claim 1,wherein spaced raised features have a parallel orientation.
 3. Theapparatus of claim 1, wherein substrate supporting feature of thecapture ring is defined on an inner perimeter of the capture ring. 4.The apparatus of claim 3, wherein the inner perimeter of the capturering at least partially circumscribes the raised features of the coverring.
 5. An apparatus for supporting a reticle, comprising: a plasmachamber having a substrate support assembly disposed therein having asubstrate supporting ridge; a plasma resistant cover ring disposed onthe substrate support assembly having a bore disposed therethrough andadapted to receive a photomask reticle during processing, the substratesupporting ridge of the substrate support assembly extending into thebore; a plasma resistant lift plate disposed on the cover ring andmovable between a lowered position that positions the reticle on thesubstrate supporting ridge in bore and a raised position that elevatesthe reticle above the cover ring.
 6. The apparatus of claim 5 furthercomprising: a plurality of movable lift pins disposed through the coverring and adapted to move the lift plate.
 7. The apparatus of claim 5,wherein upper surfaces of the lift plate and the cover ring aresubstantially coplanar when the lift plate is in the lowered position.8. The apparatus of claim 5, wherein the cover ring and lift plate havemating features.
 9. The apparatus of claim 5, wherein the bore isrectangular.
 10. The apparatus of claim 5, wherein the lift plate iscomprised of at least one of aluminum or aluminum oxide.
 11. Theapparatus of claim 5, wherein the lift plate has a substrate supportfeature defined in an inner perimeter.
 12. The apparatus of claim 11,wherein the inner perimeter further comprises opposing lower portions.13. The apparatus of claim 5, wherein the cover ring has a plurality ofraised features that define a substrate receiving slot.
 14. Theapparatus of claim 13, wherein two of the plurality of raised featuresare disposed in a parallel orientation.
 15. An apparatus for supportinga reticle, comprising: a substrate support pedestal having a substratesupporting ridge extending from an upper surface of the substratesupport pedestal; a cover ring disposed on the substrate supportpedestal, the cover ring having a plurality of lift pin holes and spacedraised features for retaining a reticle therebetween, the cover ringhaving a central opening through which the substrate supporting ridgeextends; and a capture ring disposed on the cover ring and having asubstrate supporting feature, the capture ring movable between a loweredposition that positions the reticle on the substrate supporting ridgewithin the central opening and a raised position that elevates thereticle above the cover ring and substrate supporting ridge.